Art of forming low-boiling-point hydrocarbons



R. E. HUMPHREYS ET AL ART 0F FORMING' LOW BQLING POINT HYDROGARBONS Sept. l5, 1925.

' F led July 21, 191-9 Patented Sept. 15, 1925.

UNITED STATES ROBERT E; HUMPHREYs, FRANCIS M. ROGERS, AND MAX G. PAULUs, orV WRITING;

INDIANA, AssIGNoRs To STANDARD oIL COMPANY, or CHICAGO, ILLINOIS, A

CORPORATION F INDIANA.

f 1,553,861 PATENrV-v. OFFICE.

A BT OF FQRMING LOW-BOILING-POINT HYDROCABBONS.

'V Application mea .my 21,

To all whom ltmay concern): I

Be it known that ROBERT E'. HUMPHREYS, FRANCIS M. ROGERS, and MAX Gr. PAULU'S, citizens of the United States residing at -Whiting, the county of La e and State of Indiana, have invented a new and useful Improvement in the Art of Forming Low- Boiling-Point Hydrocarbons, of which the following is a specification. l0 This process may be carried out in the apparatus diagrammatically-illustrated in the accompanying drawing.` In this 'apparat-us 1 is a still; 2 a reflux -frac-tionating condenser; 3 a final condenser preferably l5 water cooled; 4 a-receiving drum for'distillate; and 5 a gas release pipe controlled by valve 6; 7 is a valved draw-off pipe for disntillate. 8, a valved pipe through which samples of the vapors in the still can be withdrawn for test purposes.

The still is charged with a high-boiling pointhydrocarbon oil such as fuel-oil. 'Good success hasl been had with fuel-oil obtained'l from mid-continent petroleum having a Baume gravity of 33.2 and having the following fractionation:

. 10% oir at 478 F.; 20% olf at 510 F.; 'off at 532 F.; off at 554 F.; l I off at 576 F.; o' at 610 F.; olf at 632 F.; i offat 668 F.; 90% off at 712 F.; y 98% olf at 800 F. This charge is transformed into light products including naphtha having a maximum boiling point of :250 F. at rates for lo naphtha formation of-from 1.2 per cent per J.hour of the charge andupwards by subjecting the charge under theconditions hereafter stated to continued temperatures of 740 F. and upwards, the rates of conversion varying in accordance with the temperatures as hereafter shown.` 'y The foregoing naphtha. fraction is selected for definite description because it formsa convenient index to the entire con. version process. Commercial'gasoline (e.`g. of a 400 F. maximum boilin point) may be considered as formed of a 'ght fraction such as that with armaxirnum boiling point of 250 F. andra quantity of heavier maperhour Ftlirmatitfm rate o! gaso- 1919. serial N6. 312,398.

terial admixed therewith, the character- 1st1cs of 4theunxed productvarying with commercial-conditions and the purpose'for which the product is to be used. In liquid phase pyrogenesis the various fractions seein to be formed in substantially constant relative proportions, and therefore any fraction such as the one here selected is a correct index of the rformance of the process. In the practlcal manufacture of any desired commercial product usually heavier of 250 F.) this naphtha fraction will ygenerally be taken off admixed with heavier fractions, and if, under the conditions chosen for the practice of the process, the

'than the naphtha of a main boiling point product tends to come olf heavier than desired, the ,undesired fractions will be removed from those desired either by yreflux condensation Aor by subsequent fraction'ay i Mean temperature. 740 750 760 770 780-i 790 800i810 Formation ot n'aphtha pl 1.2 1.8 2.4 3.4 53's.; 12 17 blii' intinF' mi 'A lngpo reen perhour ile 2.2 7.5 12 17 The Selection of the particular conversion rate will depend upon the choice of the op-` erator and will be largely affected bythe mechanical construction of the apparatusA and its ability to withstand the Severe conditions prevailing at the higher conversion' rates. The lower conversion rates are readily attainable in a large size stillfwithout adopting unusual or unduly expensive methods of construction, whereas the higher conversion rates will, in many instances at least, require quite expensive apparatus per unit of capacity and the choice of operating conditions is therefore affected lby the redesirable while the increased runningv rates are used for the higher rates.

The above-table shows the average results ofv actual .runs wherein 'conditions were con-- vtrolled as closely as is practicable, and shows a close approximation to results which may be -attained* in practice.

figures due to inevitable variations of conditions.

, The conversion temperatures'herein given are mean temperatures observed throughout 'actual runs. As a run progresses thestock gradually changes its composition in such a way that to maintain .the vapor constitution in thefvapor space within the still such that. with a given reflux condenser, the distillate will have aconst-ant composition througl'iout `the run, it is necessary either to lower the pressure or 'elevate thetemperatureslightly, and the common practice in commercial pyf rogenesis leads us to prefer the latter eXpedient iii running for distillate of a constantcomposition. fThe mveanteniperatures here inbefore givenare those of runs` during which the temperature .was thus somewhat raised.

During the conversion` anatmosphere of` which the vapor of the' desired product constitutes approximately 4 per cent or up.- wards is maintained inl the vapor space" in theA still. lThe conditions for maintaining thisv atmosphere can be determinedfor any vgiven conversion rate by raising-.the still' contents -to the conversion temperature corresponding'to that rate and then sampling the atmosphere. If the vapo-rs of the de` sired`finished product do not approximate 4 `per cent or upwards then a higher con- `centration should be produced'by. raising the pressure upon the still/until the proper atmosphere is obtained. IThe process can then proceed efficiently, it' `being assumed -that the reflui; condenser is sufficiently ef.

Y tion of the vapors of the desired product in the vapor space in the still by still further raising the pressure.` y

It is essential to the 4productioncf commercial yields that gas which is constantly formed-throughout the process be released l from the still, as through the pipe provided for the purpose. Since Athis gas .cai'ries vapors of the desired final products it` Individual runs,y however, may vary somewhat from these should` be thoroughly vcooled as inthe ycondenser shown before being released. lt is ,I usually desirable to permit to pass over into the final-condenser, in addition to -the gas and vapor necessarily carried therewith, a

veryconsiderable quantity of vapors' of the desired product, but the extent to which these pass over, contemporaneously `with the conversion, is amatter which may be considerably varied at the option of the opeiator. -If the reflux fractionating conconcentrated in-the vapor space in the still, then it gis possible to maintain a high percentage of the reaction product in the still `during the period of conversion. If the reflux fractionating condenser be of small capacity or be entirely omitted, a high per-y centage of the conversion product will pass over during the conversion while if the concentration of vapor of thedesired product in the vapor space of the still'approximates theminimum. above4 stated then the bulk of the conversion prgducts willpass over as rapidly as'fthey areformed.M

`While We have stated the rates of conversion to be anticipated with a particular charging stock, we have found'that variations in the stock, 'While producing quite denserv be made of large capacity and the vapors ofthe 'fdesired fractions be highlyaor noticeable variations-in rates, are relatively unimportant as. comparedv with `the teinperature" variationsv readily controllableb-y the operator, a change in temperature tothe extent of arelatively few-degrees-heing sufficient kto produce these rates with any charging stocks which it fis be ieved are likely to lbe commercially available.

This lprocess results in rapidly and elliciently producing the desired products, its

especial advantage being the predictable nature of'the resulting productsv arising from the fact that, knowing the conversion rate the operator can readily vary conditions to produce Whateverparticular results he desires. Generally speaking this process is economicalof fuel, and in, most variants o f vthe process the-fuel economyfisivery high.

. y llfhe extentto which the process is carried Y d-epends upon practical conditions. In' any process generically like 'the present there is a tendencyV for coke to form slowly on the bottomand this tends 4to produce hot bottoms with dangerlofaccident, Fifty per cent atleast of the: contents of the still can 'i be safely, transformed -under normal conditions and in 'test runs, sometimes as high as seventy-per c ent'2 can ,be transformed, but,

in general, carrying of 'till/ie conversion to so high a point produces lfot bottoms with too great frequency to be safein commercial practice in any)` large size/still. In 'a small vsize still, where the surfacev to'v'olume relation is greater, the `coke forinsiin a thinner layerand the still can also be conveniently made much stronger and it may be possible with small stills to carry the conversion to a lvery conslderable extent. There will lusually be left a residue in the still. .This residue contains a small percentage of sus-v pended solid or semisolid matter and is not suitable for use as charging stock as it is drawn olf, but the major part of it is closely similar to the original charging stock and it may be rerun at atmospheric pressure to coke or to a heavy residue and .the distillate can then, if desired, be utilized as chargingstock for a second operation. What we claim as new and desire to secure by Letters Patent is:

1. The herein described improvement in the art of liquid phase pyrogenesis of highboiling point petroleum fractions consisting in treating a body of liquid petroleum in a closed receptacle, maintaining in the vapor space above the liquid an atmosphere containing approximately 4 per cent or upwards ofvapors of a desired finishedproduct having a maximum boiling point between 250 and approximately 400 F. by exerting pressure upon the receptacle, causing the con` version of portions of the body of liquid petroleum into naphtha fractions boiling at and below 250 F. at conversion rates of from 1.2 perA cent per hour of the volume of the charge to 17.7 per cent per hour of the volume ofthe charge by maintaining the liquid body at the heroin described conversion temperatures of from 740 F. to 810F., the temperature for any given rate within said range being as herein set forth,

`removing from the receptacle gasgenerated in the conversion and cooling the'gas to condense from it the vapors of the desired product.

2. The process of claim l characterized by the fact that contemporaneously with the conversion a high percentage of the desired product is distilled 'out of the receptacle.

3. The herein described improvement in the art of liquid phase pyrogenesis of highboiling point-petroleum fractions consisting in treating a body of liquid petroleum in a closed receptacle, maintaining inthe vapor taining approximately 4 per cent or upwards of vapors of a desired llinished product having a maximum boiling point between 250.I

and approximately 400 F. by exerting pressure upon the receptacle, causing the conversion of portionsof the body of liquid petroleum into naphtlia fractions boiling at and below 250 F. yat conversion rates of from 1.2 per cent per hour of the volume of the charge to 17.7 per cent per hour of the volumeof the charge yby maintaining the liquid body at the herein described conversion temperatures of from 740 F. to 810 F., the temperature forany given rate within said range being as herein set forth, removing from the receptacle gas generated in the conversion, and subjecting the vapors passed out ofthe receptacle to the action of a reflux fractionating condenser to return to the still for further pyrogenesis the fractionsheavier than the desired product.

4. The herein described improvement in the art of liquid phase pyrogenesis of highboiling point petroleum fractions consisting in treating a body of liquid petroleum in a "closed receptacle, maintaining in the vapor space above the liquid an atmosphere containing approximately 4 per cent or upwards of 'vapors of a desired finished product having a maximum boiling point of 400 F. by exerting pressure. upon the receptacle,'causing the conversion ofy portions of thebody "of liquid petroleum into fractions boiling as low as 400 F. at conversion rates of from 2.2 per cent per hour of the volume of the charge to 35 per cent per hour of the volume of the charge by maintaining the liquid body at the herein described conversion temperatures of from 740 F. to 810 F., the temperature for any given rate Within said range being as herein set forth,

removing from the receptacle gas generated in the conversion and cooling the gas to condense from it'. the vapors of the desired product.

ROBERT E. HUMPHREYS. FRANCIS M: ROGERS. MAX (Sr.Y PAULUS. 

